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MKIII BJ8 Distributer

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robolab

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As mentioned earlier, I am restoring a MKIII BJ8, built in 1967th

Here is my real question.
I've just started the overhaul of the distributor. The installed distributor in my car is a 25D6 with the number 40920. After some research on the internet I found out that for my vehicle the type 25D6-40966 should be installed. The distributor installed in my car normally was used in vehicles earlier model years
After further research, I found that the characteristics of both distributer differ in some points. Thus, for example, the maximum Advance on my 40920 model is 15 degrees, in the later model 40966 is it 18 degrees.

Now, I wonder whether the differences in the Advance-curve a significant impact on the driving behavior, since both distributer models were incorporated into BJ7 or BJ8 cars with 3 liter engines.

Can I still use the distributer 40920, or should I replace it with the later model 40966, which would be associated with considerable costs.
 
robolab said:
As mentioned earlier, I am restoring a MKIII BJ8, built in 1967th

Here is my real question.
I've just started the overhaul of the distributor. The installed distributor in my car is a 25D6 with the number 40920. After some research on the internet I found out that for my vehicle the type 25D6-40966 should be installed. The distributor installed in my car normally was used in vehicles earlier model years
After further research, I found that the characteristics of both distributer differ in some points. Thus, for example, the maximum Advance on my 40920 model is 15 degrees, in the later model 40966 is it 18 degrees.

Now, I wonder whether the differences in the Advance-curve a significant impact on the driving behavior, since both distributer models were incorporated into BJ7 or BJ8 cars with 3 liter engines.

Can I still use the distributer 40920, or should I replace it with the later model 40966, which would be associated with considerable costs.
Click to expand...
I would call Jeff at Advanced Distributor for your question. He rebuilt mine for my BJ8 and modified the advance curve for better performance.
 
Gerd,

You can use the 40920 without any problem. I have one in my 100-Six which is fitted with a tuned BJ8 engine and is producing 215bhp. You may have to play around with the weights and springs to suit your own engine.
 
In the forum of the Austin Healey Club of Germany i got the following answer:

"The 40920 distributor reaches the max. adjustment of 30° at 4000 rev / min., The distributor 40966 the max. of 36° only at 6400 rev / min. At 4000 rev / min, he has even less than 30° advance. That means the 40920 distributor is more aggressive than the 40966 distributor in lower speed ranges. Only beginning at ca. 4700 rev / min the 40966er passes 30° and is here more aggressive than the 40920.
In summary: The 40920 distributor can be used, brings in lower speed ranges greater advance than the 40966 distributor and helps at 4500 rev / min the engine to something better torque / power values. Only above 4700 rev. the 40966 distributor gives some benefits (but when do you drive at such high speeds?). So it is not necessary to change the distributer."

So i will again use the built in 40920 distributer in my BJ8. But i will order some parts from Martin Jay at distributerdoctor.com to restore the divice.


 
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